Blogs of M. Mizanur Rahman

PHP-MySQL Interview Question

Last few days I have been working to compile a question and answer set for PHP-MySQL interview questions. There are roughly 150 questions and i will be adding more as days to come. These questions and answers are compiled from different online resources. I am planning to make it a PDF version so that people download it and go through it offline. I hope i will be able to finish it soon.

NB: If you want to add any question, please add it to the comments section. I want to make it a big repository.

Here is the first set of 80 Questions and answer.

Q:1

What are the differences between Get and post methods in form submitting.
give the case where we can use get and we can use post methods?

A:1

When to use GET or POST

The HTML 2.0 specification says, in section Form
Submission (and the HTML 4.0 specification repeats this with minor
stylistic changes):

–>If the processing of a form is idempotent
(i.e. it has no lasting observable effect on the state of the
world), then the form method should be GET. Many database searches
have no visible side-effects and make ideal applications of query
forms.
—
–>If the service associated with the processing of a form has side
effects (for example, modification of a database or subscription to
a service), the method should be POST.

How the form data is transmitted?

quotation from the HTML 4.0 specification

–> If the method is “get” – -, the user agent
takes the value of action, appends a ? to it, then appends the form
data set, encoded using the application/x-www-form-urlencoded
content type. The user agent then traverses the link to this URI. In
this scenario, form data are restricted to ASCII codes.
–> If the method is “post” –, the user agent conducts an HTTP post
transaction using the value of the action attribute and a message
created according to the content type specified by the enctype
attribute.

Quote from CGI FAQ

Firstly, the the HTTP protocol specifies
differing usages for the two methods. GET requests should always be
idempotent on the server. This means that whereas one GET request
might (rarely) change some state on the Server, two or more
identical requests will have no further effect.

This is a theoretical point which is also good
advice in practice. If a user hits “reload” on his/her browser, an
identical request will be sent to the server, potentially resulting
in two identical database or
guestbook entries, counter increments, etc. Browsers may reload a
GET URL automatically, particularly if cacheing is disabled (as is
usually the case with CGI output), but will typically prompt the
user before
re-submitting a POST request. This means you’re far less likely to
get inadvertently-repeated entries from POST.

GET is (in theory) the preferred method for
idempotent operations, such as querying a database, though it
matters little if you’re using a form. There is a further practical
constraint that many systems have built-in limits to the length of a
GET request they can handle: when the total size of a request (URL+params)
approaches or exceeds 1Kb, you are well-advised to use POST in any
case.

I would prefer POST when I don’t want the status to
be change when user resubmits. And GET
when it does not matter.

Q:2

Who is the father of PHP and explain the changes in PHP versions?

A:2

Rasmus Lerdorf is known as the father of PHP.PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3
is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current
generation of PHP, which uses the
Zend engine
under the
hood. PHP 5 uses
Zend engine 2 which,
among other things, offers many additionalOOP features

Q:3

How can we submit a form without a submit button?

A:3

The main idea behind this is to use Java script submit() function in
order to submit the form without explicitly clicking any submit button.
You can attach the document.formname.submit() method to onclick,
onchange events of different inputs and perform the form submission. you
can even built a timer function where you can automatically submit the
form after xx seconds once the loading is done (can be seen in online
test sites).

Q:4

In how many ways we can retrieve the data in the result set of
MySQL using PHP?

A:4

You can do it by 4 Ways1. mysql_fetch_row.
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc

Q:5

What is the difference between mysql_fetch_object and
mysql_fetch_array?

A:5

mysql_fetch_object() is similar tomysql_fetch_array(), with one difference –
an object is returned, instead of an array. Indirectly, that means that
you can only access the data by the field names, and not by their
offsets (numbers are illegal property names).

Q:6

What is the difference between $message and $$message?

A:6

It is a classic example of PHP’s variable variables. take the
following example.$message = “Mizan”;$$message = “is a moderator of PHPXperts.”;$message is a simple PHP variable that we are used to. But the
$$message is not a very familiar face. It creates a variable name $mizan
with the value “is a moderator of PHPXperts.” assigned. break it like
this${$message} => $mizanSometimes it is convenient to be able to have variable variable
names. That is, a variable name which can be set and used dynamically.

Q:7

How can we extract string ‘abc.com ‘ from a string ‘http://info@abc.com’
using regular expression of PHP?

We can create MySQL database with the use of
mysql_create_db(“Database Name”)

Q:9

What are the differences between require and include,
include_once and require_once?

A:9

The include() statement includes
and evaluates the specified file.The documentation below also applies torequire(). The two constructs
are identical in every way except how they handle
failure. include() produces a
Warning while require() results
in a Fatal Error. In other words, userequire() if you want a missing
file to halt processing of the page.
include() does not behave this way, the script will
continue regardless.

The include_once()
statement includes and evaluates the
specified file during the execution of
the script. This is a behavior similar
to the include()
statement, with the only difference
being that if the code from a file has
already been included, it will not be
included again. As the name suggests, it
will be included just once.include_once()
should be used in cases where the same
file might be included and evaluated
more than once during a particular
execution of a script, and you want to
be sure that it is included exactly once
to avoid problems with function
redefinitions, variable value
reassignments, etc.

require_once()
should be used in cases where the same
file might be included and evaluated
more than once during a particular
execution of a script, and you want to
be sure that it is included exactly once
to avoid problems with function
redefinitions, variable value
reassignments, etc.

Q:10

Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?

A:10

Yes we can use include() more than one time in any page though it is
not a very good practice.

Q:11

What are the different tables present in MySQL, which type of
table is generated when we are creating a table in the following syntax:
create table employee (eno int(2),ename varchar(10)) ?

A:11

Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL 3.23 and as a result if
we do not specify the table name explicitly it will be assigned to the
default engine.

Q:12

Functions in IMAP, POP3 AND LDAP?

A:12

You can find these specific information in PHP Manual.

Q:13

How can I execute a PHP script using command line?

A:13

As of version 4.3.0, PHP supports a new SAPI type (Server
Application Programming Interface) named CLI which means Command Line
Interface. Just run the PHP CLI (Command Line Interface) program and
provide the PHP script file name as the command line argument. For
example, “php myScript.php”, assuming “php” is the command to invoke the
CLI program.
Be aware that if your PHP script was written for the Web CGI interface,
it may not execute properly in command line environment.

The Zend Engine is the internal compiler and runtime engine used by
PHP4. Developed by Zeev Suraski and Andi Gutmans, the Zend Engine is an
abbreviation of their names. In the early days of PHP4, it worked as
follows:The PHP script was loaded by the Zend Engine and compiled into Zend
opcode. Opcodes, short for operation codes, are low level binary
instructions. Then the opcode was executed and the HTML generated sent
to the client. The opcode was flushed from memory after execution.Today, there are a multitude of products and techniques to help you
speed up this process. In the following diagram, we show the how modern
PHP scripts work; all the shaded boxes are optional.PHP Scripts are loaded into memory and compiled into Zend opcodes.

What are the reasons for selecting lamp (Linux, apache, MySQL,
PHP) instead of combination of other software programs, servers and
operating systems?

A:19

All of those are open source resource. Security of Linux is very
very more than windows. Apache is a better server that IIS both in
functionality and security. MySQL is world most popular open source
database. PHP is more faster that asp or any other scripting language.

Q:20

How can we encrypt and decrypt a data present in a MySQL table
using MySQL?

A:20

AES_ENCRYPT () and AES_DECRYPT ()

Q:21

How can we encrypt the username and password using PHP?

A:21

The functions in this section perform encryption and decryption, and
compression and uncompression:

encryption

decryption

AES_ENCRYT()

AES_DECRYPT()

ENCODE()

DECODE()

DES_ENCRYPT()

DES_DECRYPT()

ENCRYPT()

Not available

MD5()

Not available

OLD_PASSWORD()

Not available

PASSWORD()

Not available

SHA() or SHA1()

Not available

Not available

UNCOMPRESSED_LENGTH()

Q:22

What are the features and advantages of object-oriented
programming?

A:22

One of the main advantages of OO programming is its ease of
modification; objects can easily be modified and added to a system there
by reducing maintenance costs. OO programming is also considered to be
better at modeling the real world than is procedural programming. It
allows for more complicated and flexible interactions. OO systems are
also easier for non-technical personnel to understand and easier for
them to participate in the maintenance and enhancement of a system
because it appeals to natural human cognition patterns.
For some systems, an OO approach can speed development time since many
objects are standard across systems and can be reused. Components that
manage dates, shipping, shopping carts, etc. can be purchased and easily
modified for a specific system

Q:23

What are the differences between procedure-oriented languages and
object-oriented languages?

A:23

Traditional programming has the following characteristics:Functions are written sequentially, so that a change in programming can
affect any code that follows it.
If a function is used multiple times in a system (i.e., a piece of code
that manages the date), it is often simply cut and pasted into each
program (i.e., a change log, order function, fulfillment system, etc).
If a date change is needed (i.e., Y2K when the code needed to be changed
to handle four numerical digits instead of two), all these pieces of
code must be found, modified, and tested.
Code (sequences of computer instructions) and data (information on which
the instructions operates on) are kept separate. Multiple sets of code
can access and modify one set of data. One set of code may rely on data
in multiple places. Multiple sets of code and data are required to work
together. Changes made to any of the code sets and data sets can cause
problems through out the system.Object-Oriented programming takes a radically different approach:Code and data are merged into one indivisible item – an object (the
term “component” has also been used to describe an object.) An object is
an abstraction of a set of real-world things (for example, an object may
be created around “date”) The object would contain all information and
functionality for that thing (A date
object it may contain labels like January, February, Tuesday, Wednesday.
It may contain functionality that manages leap years, determines if it
is a business day or a holiday, etc., See Fig. 1). Ideally, information
about a particular thing should reside in only one place in a system.
The information within an object is encapsulated (or hidden) from the
rest of the system.
A system is composed of multiple objects (i.e., date function, reports,
order processing, etc., See Fig 2). When one object needs information
from another object, a request is sent asking for specific information.
(for example, a report object may need to know what today’s date is and
will send a request to the date object) These requests are called
messages and each object has an interface that manages messages.
OO programming languages include features such as “class”, “instance”,
“inheritance”, and “polymorphism” that increase the power and
flexibility of an object.

Q:24

What is the use of friend function?

A:24

Sometimes a function is best shared among a number of different
classes. Such functions can be declared either as member functions of
one class or as global functions. In either case they can be set to be
friends of other classes, by using a friend specifier in the class that
is admitting them. Such functions can use all attributes of the class
which names them as a friend, as if they were themselves members of that
class.
A friend declaration is essentially a prototype for a member function,
but instead of requiring an implementation with the name of that class
attached by the double colon syntax, a global function or member
function of another class provides the match.

Q:25

What are the differences between public, private, protected,
static, transient, final and volatile?

A:25

Public: Public declared items can be accessed everywhere.Protected: Protected limits access to inherited and parent
classes (and to the class that defines the item).Private: Private limits visibility only to the class that defines
the item.Static: A static variable exists only in a local function scope,
but it does not lose its value when program execution leaves this scope.Final: Final keyword prevents child classes from overriding a
method by prefixing the definition with final. If the class itself is
being defined final then it cannot be extended.transient: A transient variable is a variable that may not
be serialized.
volatile: a variable that might be concurrently modified by multiple
threads should be declared volatile. Variables declared to be volatile
will not be optimized by the compiler because their value can change at
any time.

Q:26

What are the different types of errors in PHP?

A:26

Three are three types of errors:1. Notices: These are trivial,
non-critical errors that PHP encounters while executing a script – for
example, accessing a variable that has not yet been defined. By default,
such errors are not displayed to the user at all – although, as you will
see, you can change this default behavior.2. Warnings: These are more serious errors – for example, attempting
to include() a file which does not exist. By default, these errors are
displayed to the user, but they do not result in script termination.3. Fatal errors: These are critical errors – for example,
instantiating an object of a non-existent class, or calling a
non-existent function. These errors cause the immediate termination of
the script, and PHP’s default behavior is to display them to the user
when they take place.

Q:27

What is the functionality of the function strstr and stristr?

A:27

strstr:

Returns part of haystack
string from the first occurrence ofneedle to the end ofhaystack.If needle is not found,
returns FALSE.

If needle is not a
string, it is converted to an integer and applied as the
ordinal value of a character.

This function is case-sensitive. For
case-insensitive searches, usestristr().

there are lots of tools available for asp to PHP conversion. you can
search Google for that. the best one is available athttp://asp2php.naken.cc./

Q:30

What is the functionality of the function htmlentities?

A:30

Convert all applicable characters to HTML entities
This function is identical to htmlspecialchars() in all ways, except
with htmlentities(), all characters which have HTML character entity
equivalents are translated into these entities.

Q:31

How can we get second of the current time using date function?

A:31

$second = date(“s”);

Q:32

How can we convert the time zones using PHP?

A:32

By using date_default_timezone_get and
date_default_timezone_set function on PHP 5.1.0

<?php
// Discover what 8am in Tokyo relates to on the East Coast of the US
// Set the default timezone to Tokyo time:
date_default_timezone_set('Asia/Tokyo');
// Now generate the timestamp for that particular timezone, on Jan 1st, 2000
$stamp = mktime(8, 0, 0, 1, 1, 2000);
// Now set the timezone back to US/Eastern
date_default_timezone_set('US/Eastern');
// Output the date in a standard format (RFC1123), this will print:
// Fri, 31 Dec 1999 18:00:00 EST
echo '<p>', date(DATE_RFC1123, $stamp) ,'</p>';?>

Q:33

What is meant by urlencode and urldocode?

A:33

URLencode returns a string in which all non-alphanumeric characters
except -_. have been replaced with a percent (%)
sign followed by two hex digits and spaces encoded as plus (+)
signs. It is encoded the same way that the posted data from a WWW form
is encoded, that is the same way as in
application/x-www-form-urlencoded media type.

urldecode decodes any %##
encoding in the given string.

Q:34

What is the difference between the functions unlink and unset?

A:34

unlink() deletes the given file from the file system.
unset() makes a variable undefined.

Q:35

How can we register the variables into a session?

A:35

$_SESSION[’name’] = “Mizan”;

Q:36

How can we get the properties (size, type, width, height) of an
image using PHP image functions?

A:36

To know the Image type use exif_imagetype () function
To know the Image size use getimagesize () function
To know the image width use imagesx () function
To know the image height use imagesy() function t

Q:37

How can we get the browser properties using PHP?

A:37

By using $_SERVER['HTTP_USER_AGENT']variable.

Q:38

What is the maximum size of a file that can be uploaded using PHP
and how can we change this?

A:38

By default the maximum size is 2MB. and we can change the following
setup at php.iniupload_max_filesize = 2M

Q:39

How can we increase the execution time of a PHP script?

A:39

by changing the following setup at php.inimax_execution_time = 30
; Maximum execution time of each script, in seconds

Q:40

How can we take a backup of a MySQL table and how can we restore
it. ?

A:40

To backup: BACKUP TABLE tbl_name[,tbl_name…] TO
‘/path/to/backup/directory’
RESTORE TABLE tbl_name[,tbl_name…] FROM ‘/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or
for transferring the data to another SQL server (not necessarily a MySQL
server). The dump will contain SQL statements to create the table and/or
populate the table.
-t, –no-create-info
Don’t write table creation information (the CREATE TABLE statement).
-d, –no-data
Don’t write any row information for the table. This is very useful if
you just want to get a dump of the structure for a table!

Q:41

How can we optimize or increase the speed of a MySQL select
query?

A:41

first of all instead of using select * from table1, use select
column1, column2, column3.. from table1

Look for the opportunity to introduce index in the table you are
querying.

use limit keyword if you are looking for any specific number of
rows from the result set.

Q:42

How many ways can we get the value of current session id?

A:42

session_id() returns the session id for the current session.

Q:43

How can we destroy the session, how can we unset the variable of
a session?

A:43

session_unregister — Unregister a global variable from the current
session
session_unset — Free all session variables

Q:44

How can we destroy the cookie?

A:44

Set the cookie in past.

Q:45

How many ways we can pass the variable through the navigation
between the pages?

A:45

GET/QueryString

POST

Q:46

What is the difference between ereg_replace() and eregi_replace()?

A:46

eregi_replace() function is identical to ereg_replace() except that
this ignores case distinction when matching alphabetic
characters.eregi_replace() function is identical to ereg_replace()
except that this ignores case distinction when matching alphabetic
characters.

2 ways
a) sizeof($urarray) This function is an alias of count()
b) count($urarray)

Q:49

What is the PHP predefined variable that tells the What types of
images that PHP supports?

A:49

Though i am not sure if this is wrong or not, With the exif
extension you are able to work with image meta data.

Q:50

How can I know that a variable is a number or not using a
JavaScript?

A:50

bool is_numeric ( mixed var)
Returns TRUE if var is a number or a numeric string, FALSE otherwise.or use isNaN(mixed var)The isNaN() function is used to check if a value is not a number.

Q:51

List out some tools through which we can draw E-R diagrams for
mysql.

A:51

Case Studio
Smart Draw

Q:52

How can I retrieve values from one database server and store them
in other database server using PHP?

A:52

we can always fetch from one database and rewrite to another. here
is a nice solution of it.$db1 = mysql_connect(“host”,”user”,”pwd”)
mysql_select_db(“db1”, $db1);
$res1 = mysql_query(“query”,$db1);$db2 = mysql_connect(“host”,”user”,”pwd”)
mysql_select_db(“db2”, $db2);
$res2 = mysql_query(“query”,$db2);At this point you can only fetch records from you previous ResultSet,
i.e $res1 – But you cannot execute new query in $db1, even if you
supply the link as because the link was overwritten by the new db.so at this point the following script will fail
$res3 = mysql_query(“query”,$db1); //this will failSo how to solve that?

So mysql_connect has another optional boolean parameter which
indicates whether a link will be created or not. as we connect to the
$db2 with this optional parameter set to ‘true’, so both link will
remain live.

now the following query will execute successfully.
$res3 = mysql_query(“query”,$db1);

Thanks goes to Hasan and Hasin for this solution.

Q:53

List out the predefined classes in PHP?

A:53

Directory
stdClass
__PHP_Incomplete_Class
exception
php_user_filter

Q:54

How can I make a script that can be bi-language (supports
English, German)?

A:54

You can maintain two separate language file for each of the
language. all the labels are putted in both language files as variables
and assign those variables in the PHP source. on runtime choose the
required language option.

Q:55

What are the difference between abstract class and interface?

A:55

Abstract class: abstract classes are the class where one or more
methods are abstract but not necessarily all method has to be abstract.
Abstract methods are the methods, which are declare in its class but not
define. The definition of those methods must be in its extending class.Interface: Interfaces are one type of class where all the methods are
abstract. That means all the methods only declared but not defined. All
the methods must be define by its implemented class.

Q:56

How can we send mail using JavaScript?

A:56

JavaScript does not have any networking capabilities as it is
designed to work on client site. As a result we can not send mails using
JavaScript. But we can call the client side mail protocol mailto
via JavaScript to prompt for an email to send. this requires the client
to approve it.

Q:57

How can we repair a MySQL table?

A:57

The syntex for repairing a MySQL table is
REPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended]
This command will repair the table specified if the quick is given the
MySQL will do a repair of only the index tree if the extended is given
it will create index row by row

Q:58

What are the advantages of stored procedures, triggers, indexes?

A:58

A stored procedure is a set of SQL commands that can be compiled and
stored in the server. Once this has been done, clients don’t need to
keep re-issuing the entire query but can refer to the stored procedure.
This provides better overall performance because the query has to be
parsed only once, and less information needs to be sent between the
server and the client. You can also raise the conceptual level by having
libraries of functions in the server. However, stored procedures of
course do increase the load on the database server system, as more of
the work is done on the server side and less on the client (application)
side.Triggers will also be implemented. A trigger is effectively a type of
stored procedure, one that is invoked when a particular event occurs.
For example, you can install a stored procedure that is triggered each
time a record is deleted from a transaction table and that stored
procedure automatically deletes the corresponding customer from a
customer table when all his transactions are deleted.Indexes are used to find rows with specific column values quickly.
Without an index, MySQL must begin with the first row and then read
through the entire table to find the relevant rows. The larger the
table, the more this costs. If the table has an index for the columns in
question, MySQL can quickly determine the position to seek to in the
middle of the data file without having to look at all the data. If a
table has 1,000 rows, this is at least 100 times faster than reading
sequentially. If you need to access most of the rows, it is faster to
read sequentially, because this minimizes disk seeks.

Q:59

What is the maximum length of a table name, database name, and
fieldname in MySQL?

A:59

The following table describes the maximum length for each type of
identifier.

Identifier

Maximum Length
(bytes)

Database

64

Table

64

Column

64

Index

64

Alias

255

There are some restrictions on the characters that may appear in
identifiers:

Q:60

How many values can the SET function of MySQL take?

A:60

MySQL set can take zero or more values but at the maximum it can
take 64 values

Q:61

What are the other commands to know the structure of table using
MySQL commands except explain command?

A:61

describe Table-Name;

Q:62

How many tables will create when we create table, what are they?

A:62

The ‘.frm’ file stores the table definition.
The data file has a ‘.MYD’ (MYData) extension.
The index file has a ‘.MYI’ (MYIndex) extension,

Q:63

What is the purpose of the following files having extensions 1) .frm
2) .myd 3) .myi? What do these files contain?

A:63

In MySql, the default table type is MyISAM.
Each MyISAM table is stored on disk in three files. The files have names
that begin with the table name and have an extension to indicate the
file type.
The ‘.frm’ file stores the table definition.
The data file has a ‘.MYD’ (MYData) extension.
The index file has a ‘.MYI’ (MYIndex) extension,

Q:64

What is maximum size of a database in MySQL?

A:64

If the operating system or filesystem places a limit on the number
of files in a directory, MySQL is bound by that constraint.The efficiency of the operating system in handling large numbers of
files in a directory can place a practical limit on the number of tables
in a database. If the time required to open a file in the directory
increases significantly as the number of files increases, database
performance can be adversely affected.
The amount of available disk space limits the number of tables.
MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM
storage engine in MySQL 3.23, the maximum table size was increased to
65536 terabytes (2567 – 1 bytes). With this larger allowed table size,
the maximum effective table size for MySQL databases is usually
determined by operating system constraints on file sizes, not by MySQL
internal limits.The InnoDB storage engine maintains InnoDB tables within a tablespace
that can be created from several files. This allows a table to exceed
the maximum individual file size. The tablespace can include raw disk
partitions, which allows extremely large tables. The maximum tablespace
size is 64TB.
The following table lists some examples of operating system file-size
limits. This is only a rough guide and is not intended to be definitive.
For the most up-to-date information, be sure to check the documentation
specific to your operating system.
Operating System File-size LimitLinux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+ (using ext3 filesystem) 4TB
Solaris 9/10 16TB
NetWare w/NSS filesystem 8TB
Win32 w/ FAT/FAT32 2GB/4GB
Win32 w/ NTFS 2TB (possibly larger)
MacOS X w/ HFS+ 2TB

Q:65

Give the syntax of Grant and Revoke commands?

A:65

The generic syntax for grant is as following
> GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY
[password]
now rights can be
a) All privileges
b) combination of create, drop, select, insert, update and delete etc.We can grant rights on all databse by using *.* or some specific
database by database.* or a specific table by database.table_name
username@hotsname can be either username@localhost, username@hostname
and username@%
where hostname is any valid hostname and % represents any name, the *.*
any condition
password is simply the password of userThe generic syntax for revoke is as following
> REVOKE [rights] on [database/s] FROM [username@hostname]
now rights can be as explained above
a) All privileges
b) combination of create, drop, select, insert, update and delete etc.
username@hotsname can be either username@localhost, username@hostname
and username@%
where hostname is any valid hostname and % represents any name, the *.*
any condition

Q:66

Explain Normalization concept?

A:66

The normalization process involves getting our data to conform to
three progressive normal forms, and a higher level of normalization
cannot be achieved until the previous levels have been achieved (there
are actually five normal forms, but the last two are mainly academic and
will not be discussed).First Normal FormThe First Normal Form (or 1NF) involves removal of redundant data
from horizontal rows. We want to ensure that there is no duplication of
data in a given row, and that every column stores the least amount of
information possible (making the field atomic).Second Normal FormWhere the First Normal Form deals with redundancy of data across a
horizontal row, Second Normal Form (or 2NF) deals with redundancy of
data in vertical columns. As stated earlier, the normal forms are
progressive, so to achieve Second Normal Form, your tables must already
be in First Normal Form.Third Normal Form

I have a confession to make; I do not often use Third Normal Form. In
Third Normal Form we are looking for data in our tables that is not
fully dependant on the primary key, but dependant on another value in
the table

External Style SheetsAdvantagesCan control styles for multiple documents at once. Classes can be
created for use on multiple HTML element types in many documents.
Selector and grouping methods can be used to apply styles under complex
contextsDisadvantagesAn extra download is required to import style information for each
document The rendering of the document may be delayed until the external
style sheet is loaded Becomes slightly unwieldy for small quantities of
style definitionsEmbedded Style Sheets

Advantages

Classes can be created for use on multiple tag types in the document.
Selector and grouping methods can be used to apply styles under complex
contexts. No additional downloads necessary to receive style information

Disadvantages

This method can not control styles for multiple documents at once

Inline Styles

Advantages

Useful for small quantities of style definitions. Can override other
style specification methods at the local level so only exceptions need
to be listed in conjunction with other style methods

Disadvantages

Does not distance style information from content (a main goal of
SGML/HTML). Can not control styles for multiple documents at once.
Author can not create or control classes of elements to control multiple
element types within the document. Selector grouping methods can not be
used to create complex element addressing scenarios

Q:71

What type of inheritance that PHP supports?

A:71

In PHP an extended class is always dependent on a single base class,
that is, multiple inheritance is not supported. Classes are extended
using the keyword ‘extends’.

Q:72

What is the difference between Primary Key and
Unique key?

A:72

Primary Key: A column in a table whose values uniquely identify the
rows in the table. A primary key value cannot be NULL.

Unique Key: Unique Keys are used to uniquely identify each row in the
table. There can be one and only one row for each unique key value. So
NULL can be a unique key.There can be only one primary key for a table but there can be more
than one unique for a table.

Q:73

The structure of table view buyers is as follows:

Field

Type

Null

Key

Default

Extra

user_pri_id

int(15)

PRI

null

auto_increment

userid

varchar(10)

YES

null

the value of user_pri_id the last row 999 then What will happen in
the following conditions?

Condition1: Delete all the rows and insert another row then.
What is the starting value for this auto incremented field user_pri_id ,Condition2: Delete the last row(having the field value 999) and
insert another row then. What is the value for this auto incremented
field user_pri_id

A:73

In both cases let the value for auto increment field be n then next
row will have value n+1 i.e. 1000

Q:74

What are the advantages/disadvantages of MySQL and PHP?

A:74

Both of them are open source software (so free of cost), support
cross platform. php is faster then ASP and JSP.

Q:75

What is the difference between GROUP BY and ORDER BY in Sql?

A:75

ORDER BY [col1],[col2],…,[coln]; Tels DBMS according to what columns
it should sort the result. If two rows will hawe the same value in col1
it will try to sort them according to col2 and so on.GROUP BY
[col1],[col2],…,[coln]; Tels DBMS to group results with same value of
column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if
you want to count all items in group, sum all values or view average

Q:76

What is the difference between char and varchar data types?

A:76

Set char to occupy n bytes and it will take n bytes even if u r
storing a value of n-m bytes
Set varchar to occupy n bytes and it will take only the required space
and will not use the n bytes
eg. name char(15) will waste 10 bytes if we store ‘mizan’, if each char
takes a byte
eg. name varchar(15) will just use 5 bytes if we store ‘mizan’, if each
char takes a byte. rest 10 bytes will be free.

Q:77

What is the functionality of md5 function in PHP?

A:77

Calculate the md5 hash of a string. The hash is a 32-character
hexadecimal number. I use it to generate keys which I use to identify
users etc. If I add random no techniques to it the md5 generated now
will be totally different for the same string I am using.

Q:78

How can I load data from a text file into a table?

A:78

you can use LOAD DATA INFILE file_name; syntax to load data
from a text file. but you have to make sure thata) data is delimited
b) columns and data matched correctly

Q:79

How can we know the number of days between two given dates using
MySQL?

I was looking for this kind of interview questions ans answers. Nice work man. This kind of post will help us very much. I am waiting for full, i mean all 200 quetions and some extra questions from Hasin Vi and fom others.

Your collection of questions is really very good and valuable. I am also working on opensource projects and try to share my knowledge about PHP in my blog. I you get time please visit this also,http://asitkatiyar.wordpress.com/

Hi asit,
I have recieved ur php quetion and answer, realy it will be benificial for me in my php job,I request u that update ur qustion and answer with good example, i hope that oncentrate at this my point.

I am from Tamil Nadu. I am working as a web developer in a small Web Development Company. I want to improve my PHP and Mysql Knowledge and as well as My Communication Skills.
Please Provide some instructions to me to become a Good PHP Programmer.

Hello Syed,
Communication is not a problem first make one good environment then automatically increase your professional strength. first don’t worrying about your communication, daily update your programming strength then refer so many book and some time spent to your new friend circle. that shall.take it easy ya….

Thanks for your comment. In order to improve your PHP and MySQL knowledge always keep you updated with the current progress of these two most popular platform. You can read professional PHP 5 from wrox publication or even PHP power programming for a solid understanding of PHP Object Oriented Programming. You can study a good RDBMS book to understand how SQL works specially how to make your database optimized and operation faster. For your communication skill you can always talk with other people to increase your speaking and listening capability. for writing, start blogging 🙂

This is really very helpful only on PHP, but i think it did not cover most of the topics of MySQL like ‘why Joins are efficient than Subqueries?’,etc..
Can you please add questions related to MySQL also in place?

Thanks for the collection published. Mizan I just want to know what are the certification a person can do in php and what are the benifits of doing that in job regard. If you know please tell me the books so that i can start.

amazing work,really very helpful to use for the interview.You should place some example of php which is given a typical ans.like print $a=12==123; put some melodious and brain storming exaples in php.But nice work

I have a Quick Question currently am working as a web Designer from past 1 year…But am interested in Java Development..
what should i Do?
it is good to be web Development or shall i jump into java development…

Hi Rahman,
You’re interview questions are really superb. I get some knowledge after i go through all the questions posted above. There are some other questions asked by an interviewer in a company. They are

1.What is DDL and DML?
2. Difference between copy and move_uploaded_file
3. How to swap a value without using a third variable?
4. Which function is used to send attachment in mail?
5. Which table in mysql is used for transaction process?

hi
I am jeyasankar php developer and web developer from chennai. I am a Software Engineer by profession. I love to work on open source projects and specially web based systems. I am a moderator of the PHPExperts, the largest PHP Users group in india and chennai.
so any query ask me my mail id ,i will send replay.

I am jeyasankar php developer and web developer from chennai. I am a Software Engineer by profession. I love to work on open source projects and specially web based systems. I am a moderator of the PHPExperts, the largest PHP Users group in india and chennai.
i am experts in this area of all type server and SEO and cms.

I must say dats a wonderful compilation of exhaustive question on php & mysql too .. i will help u , if i can add more question & answer to it..
n i wud just ask u 2 give answers with some examples as far as possible..coz its much better way to explain any point.

Yesterday i faced an interview for the post of Php Developer in my city, i gave the interview and got selected just because of few questions which others didn’t knew like max size of sqldb, $$message, how to transfer one db table to another etc. . I want to say you ‘THANK YOU’. Without ur this contribution i was unable to crack that interview.
Hats Off to you Mizan.
Cheers 🙂

Mr. Machine, thanks for your response. but please read the first paragraph of this page, it clearly says these questions are taken from different site and compiled to a single place. I am not taking credit by saying that its all mine. I hope that clears your misunderstanding. 🙂 cheers.

I was looking for this kind of interview questions ans answers. Nice work sir.
I read given questions and answers i like it, it is very help full for a new comer or experience programmer in php .
now i m able to face interview.these ques r very cutial for me bcoz on 23 i”ll face a interview.
thanks a lot sir………..

Rahman,
Greets for your hardwork. If I have seen this before getting into interview i’d have got placed. I posting some PHP question which I have asked by my interviewer to reject me. Would you mind, if I tell u to check ur spelling in your posts?
🙂

What is output buffering?
What is register globals and why it is unsecure?
If particular server is accessed by many, whether would be created for all?
mysqlconnect vs mysqlpconnect ?
difference between explode and join methods()?
Given SQL table with data in one column, ‘Red’ 10 times, ‘Green’ 7 times, Blue 5 times, White 3 times, write the query to sort the elements so that the element with maximum no. of occurrence will come first and so on. (In our case it should be same order as I’ve written the elements)
Who will display a table of contents in alternate back color
Who will you show/hide particular table
How will u refresh particular section of webpage without affecting others’

hi
this is really excellent tips for me. and
this will benifit to my interview.
so pls update a qustion and answer.
pls send me question and ans on mail. about java,php and mysql.
i really thankful to u.

thanks on focusing on this. the issue reveals in which aspect php is slower than Java. and the thing you just found, i have faced the issue 3 years back while i was building a large VOIP billing software. PHP File IO is very slow and slowest of all the available programming language. So i think that is one point where we should not use PHP, i personally prefer Perl or Python for file IO. I think you also know the fact that Java IO was painfully slower and then they had to come up with new implementation of IO known as NIO. so lets see if PHP comes up with something cool and new in future.

1) does php support application context.
ans: yes you have to manage it through cookies.
2) how you will manage cookies at application level ans: while setting cookies set cookie path to application level
3)can we use session_register and cookie setting after
html start tags.
ans: no, have to use them before html start tag.

Hi,
i am sunita i have just completed my PHP,i m getting some problem regarding this,actually i have installed the software properly but still i m unable to create my database pls tell me the solun regarding this

Your answer to question 16 contradicts itself. You say that nl2br() inserts before newlines, but then you say that echo nl2br(“god bless\n you”) will output “god bless you”. The output will, in fact, be “god bless\n you”.

I think you are doing something wrong here. i think my answer is right. can you please read it carefully. i said the break will be after bless and there will be no \n once nl2br is run. so i do not know where you are getting this answer. if you write the expression in a single quote then the result will be completely different. try out by yourself 🙂

Hi
I’m looking for a way to encrypt data.
these are the steps:
1) User login to the website.
2) ask to download a file from Mysql database.
3) The system encrypt the file using user (email,passphrase).
4) The user collect the encrypted file.
5) Then decrypt the file using (email,passphrase).
6) Using any programming laguange compatible with PHP

Your questions and answers are really helpful to the ppl like me who wish to make a career as a PHP programmer.
if you aware about other good que-answers in pdf format plz give the link…anyother know plz share…

Hi I’m working as a PHP developer since 8 months i was getiing bored in my job and was planning to move to java would anyon elet me know other than web development what else we can do in PHP my concern is i have learnt PHP i don wan to let it go i want t build my own applications in PHP.

Q2. How to read content of a text file and write data into a text file in php?

Q3. What is function of the following operator in php?
= = =
What is the difference between if ($a= =$) and if ($a= = =$b)

Q4.How to calculate the length of an array?

Q5.Does the count() can calculate the length of a string array?
Q6.
$arr=”aaaaa”;
echo count($arr);
what is the output?

Q7.Suppose we are doing LEFT JOINING with two tables. It will take all records from left tables and the matching records from the right tables. If there is no match in the right
Table then it will insert null values.

The Question is write a LEFT Join query that will insert some default values in the place of null using SQL function.

Q8. What is different between unique key and primary key?
Suppose there is only one field in a table that has unique values. What key will i chose for this field? Unique key or primary key. Give explanation.

I’m Simeon Olusola Gbeleyi from Lagos, Nigeria a web developer and software developer. I really enjoy your interview questions and answers but the additional questions I need reply on include
1, how to generate random codes using php
2, how to search and display uploaded saved pictures 4rm mysql database
3, how to build a shopping cart site using php

Hi I shashi having 3 years experience in Php domain I read this articles.This is realay good for fresher as well as experienced.It gives all overview details of Php.I really like this bcause it gives confidence to deploy yourself in the market.

Both converts source code into machine language (binary data). compiler coverts program as a whole and stores in a text file and executes it. So less time consumption.
interpreter converts code line by line.

Great beat ! I would like to apprentice while you amend your website, how can i subscribe for a blog site?
The account aided me a acceptable deal. I had been tiny bit acquainted of this your broadcast
offered bright clear concept

Session:- 1) Session is created on Server-side.
2)This method is safe, because your data is stored on server side and hacker can’t hack your data.
3)Session is destoryed when you close your browser.
4)You can’t set the closing time for Session.
5) You hust create the Session_variable for your data to store in the session.

Cookies:- 1)Cookies is created on Client-side.
2)This method is not safe, because your data is stored on your own machine and hacker can hack your data.
3)Cookies is not destroyed even if you close the brwoser.You can open it within2-days.
4)You can set closing time for Cookies.
5) Cookies(name,value,time,path,domain)
Cookies(Gopal,123,time()+3600)
Here we create a cookie name=Gopal, Vlaue=123 and Time= 1 hour.

i have a mysql table in which iam trying to insert data from php using mysqli and an insert stored procedure.On the terminal the stored procedure works well and does the insert.why is it that in my php script it doesnot save the data into the database??it only enters the auto_increment id field and not the rest of the data??

About Me

I am Mizanur Rahman from Bangladesh. I am a Software Engineer by profession. I love to work on open source projects and specially web based systems. I am a moderator of the PHPExperts, the largest PHP Users group in Bangladesh. I am currently working as Head of Engineering at Telenor Health A/S

I have my own startups Informatix Technologies and TechMasters. I am an Agile enthusiast and Scrum practitioner.